Liquid ejecting head and liquid ejecting apparatus

ABSTRACT

In a liquid ejecting head, a vibration plate includes an effective displacement portion provided for each pressure chamber and an island-shaped part which is provided in the effective displacement portion at a position on the opposite side to the pressure chamber and to which one end portion of a piezoelectric vibrator is bonded; the piezoelectric vibrator has a laminate structure in which electrodes and piezoelectric material are alternately laminated; a layer at an end of one side of the piezoelectric vibrator in the laminating direction is formed of an external electrode, while a layer at an end of the other side thereof in the same direction is formed of a piezoelectric material; and the piezoelectric vibrator is disposed so as to be shifted toward the other side in the laminating direction with respect to the effective displacement portion.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/863,551 filed on Aug. 8, 2013. The entire disclosure of the aboveapplication is incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to liquid ejecting heads such as ink jetrecording heads and liquid ejecting apparatuses, and particularlyrelates to liquid ejecting heads that eject liquid through a nozzle bydisplacing a diaphragm portion defining part of a pressure chamber usinga piezoelectric element, and liquid ejecting apparatuses.

2. Related Art

Liquid ejecting apparatuses are apparatuses that include a liquidejecting head capable of ejecting liquid as a liquid droplet and ejectvarious kinds of liquids from the liquid ejecting head. As arepresentative example of liquid ejecting apparatuses, an imagerecording apparatus such as an ink jet recording apparatus (printer)that includes an ink jet recording head (hereinafter, referred to as a“recording head”), for example, and performs recording (printing) byejecting liquid ink as an ink droplet from the recording head, can becited. In recent years, liquid ejecting apparatuses have been appliedto, in addition to the above-mentioned image recording apparatus,various kinds of manufacturing apparatuses such as display manufacturingapparatuses and the like.

Some existing ink jet recording heads (hereinafter, simply called“recording heads”) have a configuration in which a vibrator unit thatincludes a plurality of piezoelectric vibrators bonded to a fixingplate, a resin case in which an accommodation space capable ofaccommodating the vibrator unit is formed, and a flow path unit that isbonded to a leading end portion of the resin case (for example, seeJP-A-2001-347660 or JP-A-6-320725) are provided. A vibration plate thatdefines part of a pressure chamber within the flow path unit isdisplaced by the piezoelectric vibrator so as to change a volume of thepressure chamber, thereby causing a pressure change in the pressurechamber so that the ink is discharged through a nozzle.

The above-mentioned piezoelectric vibrator is formed by laminating aplurality of members. Each member has electrodes formed on apiezoelectric layer. The electrodes formed between the piezoelectriclayers function as internal electrodes (individual internal electrodes,common internal electrodes). External electrodes (individual externalelectrodes, common external electrodes) connected with the internalelectrodes are formed on the outer surfaces of the piezoelectricvibrator by sputtering or the like. When driving signals from a printermain body are applied to the external electrodes via a wiring member,electric fields are supplied to the piezoelectric layers (activeportions) sandwiched between the two internal electrodes or between theexternal and internal electrodes so that the piezoelectric layers aredeformed. As a result, the piezoelectric vibrator expands or contracts.

The vibration plate has a diaphragm portion configured of a flexiblefilm for sealing an opening surface of the pressure chamber and anisland provided on the flexible film. The island is a portion to which aleading end portion of the piezoelectric vibrator is bonded, and isgenerally made of a metallic block substantially formed in a rectangularparallelepiped shape. The flexible film circumferentially surroundingthe island functions as an elastic film portion. When the piezoelectricvibrator is displaced to contract or expand, the island is displaced,whereby a volume of the pressure chamber is changed. The change in thevolume of the pressure chamber causes a change in the pressure appliedto the ink within the pressure chamber and, making use of this pressurechange, the recording head ejects the ink through the nozzle. InJP-A-2001-347660, a problem is described that a fixing plate which isbonded to a base end portion on one side surface in a laminatingdirection of the piezoelectric layers and electrodes limits thedisplacement of the piezoelectric vibrator. More specifically, a portionof the piezoelectric vibrator that is on the opposite side to the fixingplate in the laminating direction has a larger displacement than theportion on the fixing plate side (especially, changes largely at a timeof contraction). Accordingly, in JP-A-2001-347660, in order to suppressthe above problem from occurring, a configuration in which an amount ofdisplacement is suppressed at a portion on the opposite side to thefixing plate is disclosed. Further, in JP-A-6-320725, a configuration isdisclosed with which fatigue fracture of an elastic film (thin portion)and cavitation, caused by driving of a piezoelectric vibrator bonded toan island of a vibration plate, are suppressed.

These piezoelectric vibrators respectively have external electrodesformed on both side surfaces thereof in the laminating direction of thepiezoelectric layers and electrodes. In these respective piezoelectricvibrators, the thickness of the piezoelectric layers positioned on bothsides of the piezoelectric vibrator in the laminating direction of thepiezoelectric layers and electrodes varies largely depending on eachindividual piezoelectric vibrator in comparison with the thickness ofthe piezoelectric layers positioned between both sides in the laminatingdirection. Further, the thickness also varies largely between one endside and the other end side of the piezoelectric vibrator in theidentical piezoelectric vibrator. The variation in the thickness causesa variation in the active displacement of the corresponding portions ofthe piezoelectric vibrator, which in turn unfavorably influences an inkdischarge characteristic.

Accordingly, there is a piezoelectric vibrator without externalelectrodes formed on both side surfaces in the laminating direction. Inthis piezoelectric vibrator, since piezoelectric layers positioned onboth sides in the laminating direction are not supplied with electricfields so that the corresponding portions are not actively displaced,the variation in thickness is unlikely to cause a variation in thedisplacement of the corresponding portions, which in turn reduces theinfluence upon the ink discharge characteristic. However, since thenumber of inactive portions which are not actively displaced, hasincreased, the displacement amount of the piezoelectric vibratordecreases as a whole.

The above problem occurs not only in an ink jet recording apparatusequipped with an ink jet recording head for discharging ink, but also ina liquid ejecting apparatus equipped with a different liquid ejectinghead for ejecting a liquid other than ink.

SUMMARY

An advantage of some aspects of the invention is to provide a liquidejecting head capable of enhancing an amount of displacement of apiezoelectric vibrator and enhancing a discharge characteristic usingthe piezoelectric vibrator, and a liquid ejecting apparatus.

A liquid ejecting head according to an embodiment of the presentinvention is proposed to achieve the above object and includes apressure chamber communicating with a nozzle, a vibration plate definingpart of the pressure chamber, and a piezoelectric vibrator configured todisplace the vibration plate. In the liquid ejecting head, the vibrationplate includes an effective displacement portion which is a regiondisplaced in accordance with displacement of the piezoelectric vibratorand is provided for each pressure chamber, the piezoelectric vibratorhas a laminate structure in which electrodes and piezoelectric materialare alternately laminated, a layer at an end of one side (hereinafterreferred to as a first side) of the laminate structure in a laminatingdirection is an electrode while a layer at an end of the other side(hereinafter referred to as a second side) of the laminate structure inthe same direction is a piezoelectric member, and the piezoelectricvibrator is disposed so as to be shifted toward the second side in thelaminating direction with respect to the effective displacement portion.

By employing the configuration in which an electrode is formed on alayer at the end of the first side of the laminate structure in thelaminating direction while no electrode is formed on a layer at the endof the second side thereof in the laminating direction, it is possibleto make the displacement amount of the layer at the end of the firstside be large and also make the displacement amount be larger for surethan the displacement amount of the layer at the end of the second side.In comparison with a case in which electrodes are formed on layers onboth ends of the first and second sides, a magnitude relationship of thedisplacement amounts from the layer at the end of the second side towardthe layer at the end of the first side, that is, a magnituderelationship that the displacement amount becomes larger as itprogresses from the layer at the end of the second side toward the layerat the end of the first side, is always maintained between individualpiezoelectric vibrators and also between the ends of the first side andthe second side of the identical piezoelectric vibrator. Further,because the piezoelectric vibrator is disposed so as to be shiftedtoward the second side in the laminating direction with respect to theeffective displacement portion, it is possible to displace the regionson both sides from the center of the effective displacement portion inthe laminating direction as equally as possible when the piezoelectricvibrator is driven. As a result, the displacement of the piezoelectricvibrator at the time of being driven can be further effectivelyconverted to a pressure change. Furthermore, since the volume of thepressure chamber can be changed efficiently and stably by driving thepiezoelectric vibrator, it is possible to reduce problems such asvariation in a liquid amount ejected through the nozzle, variation inthe flying direction of the liquid, and the like caused by deflection inthe displacement of the piezoelectric vibrator.

It is preferable in the above configuration that the vibration plateinclude an island-shaped part which is provided at a position on theopposite side to the pressure chamber sandwiching the effectivedisplacement portion therebetween and to which one end portion of thepiezoelectric vibrator is bonded, that the island-shaped part beprovided at a center portion of the effective displacement portion inthe laminating direction, and that a configuration be employed in whichthe length of an extending portion of the island-shaped part extended toboth first and second sides in the laminating direction from a bondingportion of the island-shaped part and the piezoelectric vibrator islonger at the first side than at the second side.

It is preferable in this configuration that a configuration be employedin which the width of the extending portion of the island-shaped part onthe second side in a direction intersecting with the laminatingdirection is wider than that of other portions.

According to the above configuration, a portion on the first side of thepiezoelectric vibrator whose displacement amount is relatively large isdisposed on a portion of the island-shaped part whose width isrelatively small, while a portion on the second side of thepiezoelectric vibrator whose displacement amount is relatively small isdisposed on a portion of the island-shaped part whose width isrelatively wide. Further, in a wide-width portion where the width of theisland-shaped part is wider, a larger area range of the effectivedisplacement portion is displaced in comparison with a case of anarrow-width portion where the width of the island-shaped part isnarrower. Accordingly, it is possible to make the displacement amountsof the regions on both sides from the center of the effectivedisplacement portion in the laminating direction be further matched whenthe piezoelectric vibrator is driven. As a result, the volume of thepressure chamber can be further effectively and stably changed.

It is preferable in the above configuration that a ratio of thedimension of the island-shaped part to the dimension of the effectivedisplacement portion in the laminating direction is equal to or morethan 0.85.

According to this configuration, it is possible to efficiently convertthe displacement of the piezoelectric vibrator to a change in volume ofthe pressure chamber.

Further, in the above configuration, it is possible to employ aconfiguration in which a fixing plate is bonded to the other sidesurface of the piezoelectric vibrator at a position being shifted up toa side which is opposite to a bonding side where the island-shaped partis bonded with the piezoelectric vibrator.

A liquid ejecting head according to an embodiment of the presentinvention includes a pressure chamber communicating with a nozzle, avibration plate defining part of the pressure chamber, and apiezoelectric vibrator configured to displace the vibration plate. Inthe liquid ejecting head, the vibration plate includes an effectivedisplacement portion which is a region displaced in accordance withdisplacement of the piezoelectric vibrator and is provided for eachpressure chamber and also includes an island-shaped part which isprovided at a position on the opposite side to the pressure chambersandwiching the effective displacement portion therebetween and to whichone end portion of the piezoelectric vibrator is bonded, thepiezoelectric vibrator has a laminate structure in which electrodes andpiezoelectric material are alternately laminated, a layer at an end ofone side (hereinafter referred to as a third side) of the piezoelectricvibrator in the laminating direction is an electrode while a layer at anend of the other side (hereinafter referred to as a fourth side) of thepiezoelectric vibrator in the same direction is a piezoelectric member,and the island-shaped part is disposed so as to be shifted toward thefourth side in the laminating direction with respect to the effectivedisplacement portion.

According to the above configuration, by employing the configuration inwhich an electrode is formed on the layer at the end of the third sideof the laminate structure in the laminating direction while no electrodeis formed on the layer at the end of the second side of the laminatestructure in the same direction, it is possible to make the displacementamount of the layer at the end of the third side be large and also makethe displacement amount be larger for sure than the displacement amountof the layer at the end of the fourth side. In comparison with a case inwhich electrodes are formed on layers at both ends of the third andfourth sides, a magnitude relationship of the displacement amounts fromthe layer at the end of the fourth side toward the layer at the end ofthe third side, that is, a magnitude relationship that the displacementamount becomes larger as it progresses from the layer at the end of thefourth side toward the layer at the end of the third side, is alwaysmaintained between individual piezoelectric vibrators and also betweenthe ends of the third side and the fourth side of the identicalpiezoelectric vibrator. Further, because the island-shaped part isprovided so as to be shifted toward the fourth side in the laminatingdirection with respect to the effective displacement portion, it ispossible to displace the regions on both sides from the center of theeffective displacement portion in the laminating direction as equally aspossible via the island-shaped part when the piezoelectric vibrator isdriven. As a result, the displacement of the piezoelectric vibrator atthe time of being driven can be further effectively converted to apressure change. Furthermore, since the volume of the pressure chambercan be changed efficiently and stably by driving the piezoelectricvibrator, it is possible to reduce problems such as variation in aliquid amount ejected through the nozzle, variation in the flyingdirection of the liquid, and the like caused by deflection in thedisplacement of the piezoelectric vibrator.

It is preferable in the above configuration that the piezoelectricvibrator be provided at a center portion of the effective displacementportion in the laminating direction, and a configuration be employed inwhich the length of an extending portion of the island-shaped partextended to both sides in the laminating direction from a bondingportion of the island-shaped part and the piezoelectric vibrator islonger at the fourth side than at the third side.

A liquid ejecting apparatus according to an embodiment of the presentinvention includes at least one of the liquid ejecting heads accordingto the above configurations.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described with reference to theaccompanying drawings, wherein like numbers reference like elements.

FIG. 1 is a schematic view of a printer.

FIG. 2 is a cross-sectional view of a recording head.

FIG. 3 is a perspective view of a vibrator unit.

FIGS. 4A and 4B are views of the periphery of a vibrator unit.

FIG. 5 is a waveform diagram of an ejection driving pulse.

FIG. 6A through FIG. 6C are cross-sectional views of a pressure chamberin a short-length direction thereof showing movement of a diaphragmportion at a time of ink ejection.

FIG. 7A through FIG. 7C are cross-sectional views of a pressure chamberin a lengthwise direction thereof showing movement of a diaphragmportion at a time of ink ejection.

FIGS. 8A and 8B are views of the periphery of a vibrator unit accordingto a second embodiment.

FIG. 9 is a cross-sectional view of a vibrator unit.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments for implementing the present invention will bedescribed with reference to the accompanying drawings. Although variousfeatures are placed in the embodiments described below as preferredexamples of the present invention, the scope of the present invention isnot limited thereto. Note that in the following embodiments, as a liquidejecting apparatus of the present invention, an ink jet recordingapparatus (hereinafter, called a “printer”) equipped with an ink jetrecording head (hereinafter, called a “recording head”), which is a typeof a liquid ejecting head, is cited and explained.

FIG. 1 is a view illustrating a configuration of a printer 1. Theprinter 1 is generally configured of a carriage 4 on which a recordinghead 2 is mounted and an ink cartridge 3, which is a type of a liquidsupply source, is also mounted in a detachable manner, a platen 5disposed under the recording head 2 in recording operation, a carriagemovement mechanism 7 configured to move the carriage 4 back and forth ina paper width direction of recording paper 6 (a type of a recordingmedium and a landing target), in other words, in a main scanningdirection, and a paper transport mechanism 8 configured to transport therecording paper 6 in a sub scanning direction that is orthogonal to themain scanning direction.

The carriage 4 is attached in a movable manner to a guide rod 9installed along the main scanning direction, and is configured so as tomove in the main scanning direction along the guide rod 9 driven by ofthe carriage movement mechanism 7. The position of the carriage 4 in themain scanning direction is detected by a linear encoder 10, and adetection signal thereof, in other words, an encoder pulse (a type ofpositional information) is transmitted to a controller of the printermain body (not shown). The linear encoder 10 is a type of positionalinformation outputting means, and outputs an encoder pulse EP inaccordance with a scanning position of the recording head 2 aspositional information in the scanning direction.

Within a movement range of the carriage 4, a home position as a basepoint for scanning operation of the carriage is provided in an endregion at the outside of a recording region. At the home position in thepresent embodiment, there are disposed a capping member 11 for sealing anozzle formation surface (nozzle plate 24: see, e.g., FIG. 2 and FIG.4A) of the recording head 2 and a wiper member 12 for wiping the nozzleformation surface. The printer 1 is configured so as to perform what iscalled “bidirectional recording” in which characters, images, and thelike are recorded on the recording paper 6 during the carriage 4 movingbi-directionally, that is, during the forward movement of the carriage 4from the home position toward an end portion located on the oppositeside and the backward movement from the end portion on the opposite sidetoward the home position.

FIG. 2 is a cross-sectional view of the recording head 2. FIG. 3 is aperspective view of a vibrator unit 16. FIGS. 4A and 4B are views of theperiphery of the vibrator unit 16. More specifically, FIG. 4A is across-sectional view of the vibrator unit 16 and a flow path unit 17, inwhich a case 15 is not illustrated. FIG. 4B is a plan view of adiaphragm portion 33 of a vibration plate 25 when viewed from above inthe vertical direction (from the vibrator unit 16 side), and illustratesa configuration corresponding to one piezoelectric vibrator 20.

The recording head 2 in the present embodiment includes the case 15, thevibrator unit 16 accommodated in the case 15, and the flow path unit 17bonded to a bottom surface (leading end surface) of the case 15. Thecase 15 is made of, for example, an epoxy-based resin, and anaccommodation space 18 for accommodating the vibrator unit is formedinside the case 15. The vibrator unit 16 includes a plurality ofpiezoelectric vibrators 20, a metallic fixing plate 21 to which thepiezoelectric vibrators 20 are bonded, and a flexible cable 22configured to supply the piezoelectric vibrators 20 with driving signalsand the like. The piezoelectric vibrator 20 is a laminate structure-typecomponent in which piezoelectric material and electrodes are alternatelylaminated, and is a longitudinal vibration-mode piezoelectric vibrator(lateral field effect type) that is capable of expanding and contractingin a displacement amount defined by a piezoelectric constant D31 in adirection orthogonal to the laminating direction (electric fileddirection).

The piezoelectric vibrator 20 is manufactured through the followingprocesses: that is, a process in which internal electrode material(i.e., a common internal electrode 39 and an individual internalelectrode 40) are formed (printed) on surfaces of each of piezoelectricmaterial 41 made of zirconia, lead zirconate titanate, or the like toproduce base members first, subsequently a plurality of base members arelaminated so that the piezoelectric material 41, the electrodes (i.e.,the common internal electrode 39 and the individual internal electrode40) are disposed alternately in a layered manner; a process in which apiezoelectric plate of a laminate structure is baked; a process in whichexternal electrodes (i.e., a common external electrode 42 and anindividual external electrode 43) are formed on an outer surface of thebaked piezoelectric plate by sputtering or the like; and a process inwhich the piezoelectric plate on which the external electrodes (i.e.,the common external electrode 42 and the individual external electrode43) are formed is cut and divided in a comb-toothed manner. Each combtooth made by cutting and dividing the piezoelectric plate functions aspart of the piezoelectric vibrator 20 corresponding to each pressurechamber 28. Note that, in the above manufacturing processes, a warp inthe piezoelectric plate having been baked is ground to be flat bylapping processing. Since variation in amount of polishing is large inthe lapping processing, it is necessary to take a large cutting amounton the outmost surface of the piezoelectric plate having been baked.Moreover, a variation in the thickness is also large after the lappingprocessing, in particular, a layer at a side end in the laminatestructure is likely to vary in thickness. Accordingly, in aconfiguration in which electrodes are formed on layers on both sideends, because the electrodes on both sides vary in thickness, stablecharacteristics are unlikely to be obtained for the vibrator unit. Thereis a method such that the thicknesses of the respective layers of thepiezoelectric material 41 are controlled to be as uniform as possible soas to suppress a warp in the piezoelectric plate having been baked asmuch as possible, thereby omitting the lapping processing. However,having experienced cleaning processing and cut-and-divide processing inthe manufacturing processes, layers at the side ends in the laminatestructure are likely to vary in thickness so as to unfavorably influencecharacteristics for the vibrator unit. These problems are solved in thevibrator unit 16 of the present embodiment, which will be describedlater.

The piezoelectric vibrator 20 of the present embodiment is formed byalternately laminating the common internal electrodes 39 and theindividual internal electrodes 40 while sandwiching the piezoelectricmaterial 41 therebetween. The common internal electrodes 39 are anelectrode which is common to all the piezoelectric vibrators 20 and towhich a ground potential or a bias potential is applied. The individualinternal electrodes 40 are an electrode whose potential varies inaccordance with an ejection driving pulse DP of a driving signal beingapplied thereto (see FIG. 5). In the present embodiment, from a vibratorleading end of the piezoelectric vibrator 20 (a side bonded to anisland-shaped part 35), approximately two thirds of the length of thepiezoelectric vibrator in a vibrator lengthwise direction (a directionorthogonal to the laminating direction) corresponds to a free endportion 20 a. The remaining part of the piezoelectric vibrator 20, inother words, a portion from a base end of the free end portion 20 a upto a vibrator base end corresponds to a base end portion 20 b.

The individual external electrode 43 is formed continuously from aboundary between the free end portion 20 a and the base end portion 20 bon a wiring connection surface as one side surface in the laminatingdirection (surface on the left side in FIG. 4A) across a leading endsurface of the free end portion 20 a. The individual external electrode43 is connected with the individual internal electrodes 40 at theleading end surface of the free end portion 20 a. Further, an individualwiring electrode 22 a of the flexible cable 22 is electrically connectedto the individual external electrode 43. Accordingly, the individualexternal electrode 43 makes the individual wiring electrode 22 a and theindividual internal electrodes 40 be electrically connected with eachother. The common external electrode 42 is an electrode which is formedcontinuously from the boundary between the free end portion 20 a and thebase end portion 20 b on the wiring connection surface across a base endsurface of the piezoelectric vibrator 20 which is on the opposite sideto the leading end surface thereof, and is electrically connected withthe common internal electrodes 39 at the base end surface. A commonwiring electrode 22 b of the flexible cable is electrically connected tothe common external electrode 42. Accordingly, the common externalelectrode 42 makes the common wiring electrode 22 b and the commoninternal electrodes 39 be electrically connected with each other.

The individual external electrode 43 and the common external electrode42 on the wiring connection surface are cut off and electricallyinsulated from each other by a slit 44 (a portion where the electrodematerial is removed in a slit-like form) provided along an alignmentdirection of the piezoelectric vibrators 20. As described above, in thepiezoelectric vibrator 20, a layer at an end of a surface of one side(hereinafter referred to as the first side) in the laminating directionincludes the electrodes 42 and 43, whereas no electrode material isformed on a surface of the other side (hereinafter referred to as thesecond side), i.e., a bonding surface to which the fixing plate 21 isbonded, in the laminating direction and the piezoelectric material 41(41 s) is exposed as a layer at the end of the second side. The fixingplate 21 is bonded to this surface of the second side at the base endportion 20 b side. Accordingly, the piezoelectric vibrator 20 issupported by the fixing plate 21 in what is called a cantilever manner.Protective films are formed on the surfaces of the layers on both theside ends in the laminating direction in some cases.

In the free end portion 20 a, an active portion A is formed in which thepiezoelectric material 41 is sandwiched between the common internalelectrode 39 and the individual internal electrode 40 or the individualexternal electrode 43. Applying a potential difference to the internalelectrodes 39 and 40 causes the piezoelectric material 41 of the activeportion A to deform so that the free end portion 20 a is displaced toexpand or contract in the vibrator lengthwise direction. On the otherhand, a layer at the end of the second side of the free end portion 20 ais the piezoelectric material 41 s and an electric field is not appliedto this piezoelectric material 41 s. Accordingly, this portion becomesan inactive portion B that is not displaced when the piezoelectricvibrator 20 is driven. In FIG. 4A, the inactive portion B in which bothsides of the piezoelectric material 41 are not sandwiched between thecommon internal electrodes 39 and the individual internal electrode 40or the individual external electrode 43 is indicated by hatchingincluding the piezoelectric material 41 s.

At the time of the piezoelectric vibrator 20 being driven, because thepiezoelectric material 41 s of the layer at the end of the second side,which is part of the inactive portion, limits the expansion andcontraction of the piezoelectric vibrator 20, the displacement amount(absolute value) of the piezoelectric vibrator 20 being driven isrelatively large at the first side, whereas the displacement amountbecomes smaller as it progresses toward the second side (thepiezoelectric material 41 s side). The piezoelectric vibrator 20 of thisconfiguration, in comparison with a piezoelectric vibrator of theexisting configuration in which an external electrode is formed on thesurface of the second side (the layer at the end of the second side isan external electrode), can have a relatively large amount ofdisplacement at the first side like the existing piezoelectric vibrator;moreover, the displacement amount at the first side can be made largerthan that at the second side with certainty, that is, it can be madelarge in a stable manner. Therefore, even if there exists a variation inthe thickness of the piezoelectric layers, a magnitude relationship ofthe displacement amounts from the layer at the end of the second sidetoward the layer at the end of the first side, that is, a relationshipthat the displacement amount becomes larger as it progresses from thelayer at the second side toward the layer at the first side, is alwaysmaintained between the individual piezoelectric vibrators and alsobetween the end of the first side and the end of the second side of theidentical piezoelectric vibrator, thereby making it possible to obtain astable displacement-operation characteristic (displacement amountcharacteristic). In particular, a large amount of displacement can beobtained for sure (stably) at the first side opposite to the second sidewhere the fixing plate is bonded. Accordingly, the volume of thepressure chamber 28 can be more efficiently changed by making use of theabove characteristic appropriately. This point will be described indetail later.

A costly rare metal is used for the electrodes; however, as describedabove, no external electrode is formed on the surface of the second sideof the piezoelectric vibrator 20 in the laminating direction.Accordingly, costs can be suppressed by the amount corresponding to apotential cost of the rare metal not being used. Further, there exists arisk of generation of a defect called a spot in the external electrodein the manufacturing process, or a risk of generation of a short circuitbetween the piezoelectric vibrators due to burrs or the like producedwhen the cut-and-divide processing is performed. However, because noexternal electrode is formed on the surface of the second side, it ispossible to lower the risk of generation of the defect, and to enhancethe yield.

The flow path unit 17 is configured so that the nozzle plate 24 isbonded to one surface of a flow path formation substrate 23 and thevibration plate 25 is bonded to the other surface of the flow pathformation substrate 23. In the flow path unit 17, there are provided areservoir 26 (common liquid chamber), an ink supply port 27, thepressure chamber 28, a nozzle communication port 29, and a nozzle 30. Anink flow path (liquid flow path) continuously extending from the inksupply port 27 to the nozzle 30 via the pressure chamber 28 and thenozzle communication port 29 is provided corresponding to each nozzle30. The pressure chamber 28 is configured of a space elongated in adirection orthogonal to a nozzle row to be explained later, and theupper surface thereof (surface on the side where the vibration plate 25is bonded) is opened. One end portion of the pressure chamber 28 in alengthwise direction thereof communicates with the nozzle 30 via thenozzle communication port 29 penetrating through the flow path formationsubstrate 23 in a thickness direction, while the other end portionthereof in the lengthwise direction communicates with the reservoir 26via the ink supply port 27. An upper side opening of the pressurechamber 28 is sealed by the vibration plate 25. Further, on the upperside opening of the pressure chamber 28 in a sealed state, there isdisposed the diaphragm portion 33, details of which will be describedlater.

The nozzle plate 24 is a thin metallic plate (stainless steel, forexample) in which a plurality of nozzles 30 are bored in a row at apitch corresponding to a dot formation density (for example, 180 dpi). Aplurality of nozzle rows (nozzle groups) including the aligned nozzles30 are provided on the nozzle plate 24, and one nozzle row is configuredof 180 nozzles 30, for example. The nozzle plate 24 is made of othermaterial such as a silicon single crystal substrate or the like in somecases.

The vibration plate 25 has a two-tier structure in which a flexible film32 is laminated on a surface of a support plate 31. In the presentembodiment, the vibration plate 25 is configured with a composite boardin which a resin film is laminated as the flexible film 32 on thesurface of the support plate 31 that is made of a metal plate such as astainless steel or the like. In the vibration plate 25, the diaphragmportion 33 configured to change the volume of the pressure chamber 28 isformed at a portion corresponding to each pressure chamber 28 of theliquid flow formation substrate 23. Further, in the vibration plate 25,a compliance portion 34 configured to seal the reservoir 26 is providedat a portion corresponding to the reservoir 26 of the flow pathformation substrate 23. The compliance portion 34 is manufactured asfollows: that is, the support plate 31 present in a region facing anopening surface of the reservoir 26 is removed by etching or the like sothat only the flexible film 32 is present in this region. The complianceportion 34 functions as a damper for absorbing a pressure change inliquid stored in the reservoir 26.

Like the compliance portion 34, the diaphragm portion 33 is manufacturedby partly removing the support plate 31 by etching. That is, thediaphragm portion 33 is configured of the island-shaped part 35 to whichthe leading end surface of the piezoelectric vibrator 20 is bonded andan elastic film portion 36 which is formed of only the flexible film 32surrounding the circumference of the island-shaped part 35. The elasticfilm portion 36 is a portion where the support plate 31 is removedacross a formation range of the pressure chamber 28 while the supportplate 31 serving as the island-shaped part 35 is left. Of the diaphragmportion 33, a portion that seals the upper side opening of the pressurechamber 28 and is actually displaced in accordance with the expansionand contraction of the piezoelectric vibrator 20 (a portion includingthe island-shaped part 35 and the elastic film portion 36 present in thecircumference of the island-shaped part 35), corresponds to an effectivedisplacement portion. When the dimension of the effective displacementportion in the laminating direction of the piezoelectric material andelectrodes (hereinafter, simply called the “laminating direction”) istaken as L1, the dimension of the island-shaped part 35 in the samedirection is taken as L2, a relation of L2/L1≧0.85 is being set (notethat L2/L1 is less than 1). With this, the displacement of thepiezoelectric vibrator 20 can be efficiently converted to a change involume of the pressure chamber 28. The island-shaped part 35 is disposedat a position on the opposite side to the pressure chamber 28sandwiching the elastic film portion 36 of the effective displacementportion therebetween. The piezoelectric vibrator 20 can displace thediaphragm portion 33, that is, displace the effective displacementportion via the island-shaped part 35.

In FIG. 4B, a portion that corresponds to the elastic film portion 36 ofthe diaphragm portion 33 is indicated by a whitened rectangle shape.However, the effective displacement portion is not necessarily a regionhaving a rectangle shape when viewed from above because the effectivedisplacement portion is determined in accordance with a shape of theopening of the pressure chamber 28; for example, if the shape of theopening of the pressure chamber is a parallelogram, the effectivedisplacement portion becomes a parallelogram-shaped region following theshape of the opening. In FIG. 4B, the center of the effectivedisplacement portion (center in the laminating direction) is taken asC1. Likewise, the center of the piezoelectric vibrator 20 (center in thelaminating direction) is taken as C2.

The recording head 2 of the present embodiment is characterized in thatthe leading end surface of the piezoelectric vibrator 20 is bonded tothe island-shaped part 35 in a state in which the piezoelectric vibrator20 is off-center with respect to the diaphragm portion 33 (effectivedisplacement portion). To be more specific, with respect to the centerC1 of the effective displacement portion, the center C2 of thepiezoelectric vibrator 20 is disposed off-center toward the second sidein the laminating direction, in other words, off-center toward the sideof the piezoelectric material 41 s which is a layer at the side end andis the inactive portion B. On the other hand, the center of theisland-shaped part 35 in the laminating direction substantially matchesthe center C1 of the effective displacement portion. That is to say, theisland-shaped part 35 is disposed at a center portion of the effectivedisplacement portion. With this, in a state in which the leading endsurface of the piezoelectric vibrator 20 is bonded to the island-shapedpart 35, the length of an extending portion of the island-shaped part 35extended to both sides in the laminating direction from a bondingportion of the island-shaped part 35 and the piezoelectric vibrator 20is longer at the first side than at the second side. In other words, ifthe length of the extending portion on the first side (nozzlecommunication port 29 side) is taken as L3 and the length of theextending portion on the second side (ink supply port 27 side) is takenas L4, a relation of L3>L4 holds. As described above, by making thepiezoelectric vibrator 20 off-center toward the second side in thelaminating direction with respect to the effective displacement portion,a portion of the free end portion 20 a at the first side whosedisplacement amount is relatively large is disposed closer to the centerC1 of the effective displacement portion; accordingly, it is possible todisplace the regions on both sides from the center C1 of the effectivedisplacement portion in the laminating direction as equally as possiblewhen the piezoelectric vibrator 20 is driven. In other words, a volumeof the pressure chamber 28 that has been changed to due to thedisplacement of the effective displacement portion on the first sidefrom the center C1 of the effective displacement portion in thelaminating direction and a volume of the pressure chamber 28 that hasbeen changed to due to the displacement of the effective displacementportion on the second side from the center C1 in the laminatingdirection, are substantially equivalent to each other when thepiezoelectric vibrator 20 is driven.

In the case where the center C1 of the effective displacement portionand the center C2 of the piezoelectric vibrator C2 are made to matcheach other, the displacement of the region on the first side from thecenter C1 of the effective displacement portion becomes relativelylarge, whereas the displacement on the second side from the center C1 ofthe effective displacement portion becomes relatively small. Incontrast, by making the piezoelectric vibrator 20 off-center toward thesecond side in the laminating direction with respect to the effectivedisplacement portion, the displacement of the region on the second sidefrom the center C1 of the effective displacement portion can be largerthan that of the above case, whereby the displacement on both sides fromthe center C1 of the effective displacement portion can be made uniform.That is, the amounts of changes in volume of the pressure chamber 28generated on both sides from the center C1 due to the above-mentioneddisplacement can be made uniform. That is, the degrees of pressurechanges generated in the ink within the pressure chamber 28 on bothsides from the center C1 can be made equivalent to each other. As aresult, while reducing problems such as variation in the ink amountejected through the nozzle 30, variation in the flying direction of theink, and the like caused by deflection in the displacement of thepiezoelectric vibrator 20, it is possible to effectively make use ofsuch an advantage of the piezoelectric vibrator that an absolutedisplacement amount is large when a predetermined potential is applied,whereby the volume of the pressure chamber 28 can be changed efficientlyand stably.

As shown in FIG. 4B, in the present embodiment, a width W1 of theisland-shaped part 25 on the second side (dimension in a directionorthogonal to the laminating direction) in a lengthwise direction of theisland-shaped part 25 (laminating direction of the piezoelectricvibrator 20) is wider than a width W2 on the first side in the samedirection thereof. To be more specific, in a state of the piezoelectricvibrator 20 being bonded, a portion on the second side from the centerC2 of the piezoelectric vibrator in the laminating direction correspondsto a wide-width portion 35 w whose width is wider than that of otherportion (a narrow-width portion 35 n). The width W1 of the wide-widthportion 35 w is set narrower than the width of the effectivedisplacement portion.

In a state in which the piezoelectric vibrator 20 is positioned withrespect to the island-shaped part 35 (positioned off-center with respectto the effective displacement portion, as described above), a portion ofthe piezoelectric vibrator 20 (free end portion 20 a) on the first sidewhose displacement amount is relatively large is disposed at thenarrow-width portion 35 n of the island-shaped part 35, while theinactive portion B (piezoelectric material 41 s) of the piezoelectricvibrator 20 on the second side whose displacement amount is relativelysmall is disposed at the wide-width portion 35 w of the island-shapedpart 35. Since the wide-width portion 35 w displaces a wider range ofthe elastic film portion 36 than the narrow-width portion 35 n, it ispossible to further match the respective displacement amounts of theregions on both sides from the center C1 of the effective displacementportion when the piezoelectric vibrator 20 is driven. Consequently, thevolume of the pressure chamber 28 can be changed further efficiently andstably.

FIG. 5 is a waveform diagram illustrating an example of a configurationof the ejection driving pulse DP for driving the piezoelectric vibrator20 so as to eject ink through the nozzle 30. In FIG. 5, the verticalaxis represents a potential and the horizontal axis represents time. Theejection driving pulse DP includes an expansion element p1 in which thepotential changes toward a potential increasing side from a basepotential (intermediate potential) Vb up to a maximum potential (maximumvoltage) Vmax so as to expand the pressure chamber 28, an expansionholding element p2 for holding the maximum potential Vmax for a setperiod of time, a contraction element p3 in which the potential changestoward a potential decreasing side from the maximum potential Vmax downto a minimum potential (minimum voltage) Vmin so as to rapidly contractthe pressure chamber 28, a contraction holding (vibration-suppressionholding) element p4 for holding the minimum potential Vmin for a setperiod of time, and a return element p5 in which the potential returnsto the base potential Vb from the minimum potential Vmin.

FIG. 6A through FIG. 6C are cross-sectional views of the pressurechamber 28 in a short-length direction thereof (a direction orthogonalto the laminating direction) for describing the movement of thediaphragm portion 33 (effective displacement portion) at a time when inkis ejected through the nozzle 30 by driving the piezoelectric vibrator20. FIG. 7A through FIG. 7C are cross-sectional views of the pressurechamber 28 in the lengthwise direction thereof (laminating direction)for describing the movement of the diaphragm portion 33 (effectivedisplacement portion) at the time when ink is similarly ejected.

The ejection driving signal DP makes the following action take placewhen it is applied to the piezoelectric vibrator 20. In the case wherethe potential applied to the piezoelectric vibrator 20 is at the basepotential Vb, which is a start potential and also an end potential ofthe ejection driving pulse DP, the island-shaped part 35 is positionedin the vicinity of the opening portion of the pressure chamber 28 asshown in FIG. 6A and FIG. 7A. When the ejection driving pulse DP isapplied to the piezoelectric vibrator 20, the piezoelectric vibrator 20is made to contract in a direction orthogonal to the laminatingdirection by the expansion element p1. Since the circumference of theisland-shaped part 35 (within the effective displacement portion) isoccupied by the elastic film portion 36, deformation of this elasticfilm portion 36 allows the displacement of the island-shaped part 35(displacement of the effective displacement portion) following thecontraction of the piezoelectric vibrator 20. That is, as shown in FIG.6B and FIG. 7B, when the piezoelectric vibrator 20 contracts, theisland-shaped part 35 is displaced toward a side apart from the pressurechamber 28 (opposite side to the nozzle plate 24) following thecontraction of the vibrator. In this case, because the piezoelectricvibrator 20 is disposed off-center toward the other side with respect tothe effective displacement portion, variations in the displacementamounts of the piezoelectric vibrator 20 in the laminating direction arecancelled out, thereby making it possible to displace the effectivedisplacement portion as uniformly as possible. Due to this displacement,the pressure chamber 28 is made to expand from a base volumecorresponding to the base potential Vb to a maximum volume correspondingto the maximum potential Vmax. The expansion of the pressure chamber 28causes a meniscus exposed in the nozzle 30 to be pulled in toward thepressure chamber side.

The expansion state of the pressure chamber 28 is held constant for aperiod of time during which the expansion holding element p2 is applied.During the above period of time, since the piezoelectric vibrator 20holds the contraction state thereof, the island-shaped part 35 holds itsposition as well. When the contraction element p3, following theexpansion holding element p2, is applied to the piezoelectric vibrator20, the piezoelectric vibrator 20 is made to expand to the maximum orapproximately to the maximum. Also in this case, because thepiezoelectric vibrator 20 is disposed off-center toward the second sidewith respect to the effective displacement portion, it is possible todisplace the effective displacement portion as uniformly as possible.With this, as shown in FIG. 6C and FIG. 7C, the island-shaped part 35 israpidly displaced toward a side approaching the pressure chamber 28(nozzle plate 24 side). This causes the pressure chamber 28 to contractrapidly from the above-mentioned maximum volume to a minimum volumecorresponding to the minimum potential Vmin. The rapid contraction ofthe pressure chamber 28 pressurizes ink in the pressure chamber 28 sothat several p1 (picoliters) to several tens of p1 of ink is ejectedthrough the nozzle 30. The contraction state of the pressure chamber 28is held for a short period of time during which the contraction holdingelement p4 is applied. During the above period of time, since thepiezoelectric vibrator 20 holds the expansion state thereof, theisland-shaped part 35 holds its position as well. Thereafter, the returnelement p5 is applied to the piezoelectric vibrator 20 so that thepiezoelectric vibrator 20 is made to contract. Following thecontraction, the island-shaped part 35 is displaced to a stationaryposition corresponding to the base potential Vb. This causes thepressure chamber 28 to return to the base volume.

As described thus far, the recording head 2 employs the piezoelectricvibrator 20 of the configuration in which an external electrode isformed on a layer at the end of the first side of the laminate structurein the laminating direction while no electrode is formed on a layer atthe end of the second side of the laminate structure in the samedirection. Accordingly, in comparison with the existing configuration inwhich electrodes are formed on layers on both the side ends, it ispossible to obtain a relatively large displacement amount on the firstside like in the existing configuration, and it is also possible to makethe displacement amount on the first side be larger with certainty thanthe displacement amount on the second side, that is, it is possible tomake the displacement amount on the first side be stably large. In orderto appropriately make use of the characteristics and advantages of thepiezoelectric vibrator 20, the piezoelectric vibrator 20 is disposedbeing off-center toward the side of the piezoelectric material 41 s asthe inactive portion B (toward the second side) with respect to theeffective displacement portion of the diaphragm portion 33, so that theregions on both sides from the center C1 of the effective displacementportion in the laminating direction can be displaced as equally aspossible when the piezoelectric vibrator 20 is driven. This makes itpossible to efficiently convert the expansion and contraction of thepiezoelectric vibrator 20 to the change in volume of the pressurechamber 28. As a result, while reducing the problems such as variationin the ink amount ejected through the nozzle 30, variation in the flyingdirection of the ink, and the like caused by deflection in thedisplacement of the piezoelectric vibrator 20, it is possible toeffectively make use of such an advantage of the piezoelectric vibrator20 that an absolute displacement amount is large when a predeterminedpotential is applied, whereby the volume of the pressure chamber 28 canbe changed efficiently and stably.

In addition, the discharge characteristic and the displacement amountcan be enhanced in the printer 1 having the recording head 2.

Note that the present invention is not intended to be limited to theabove embodiment, and various kinds of variations can be made.

FIGS. 8A and 8B are views of the periphery of a vibrator unit 16according to a second embodiment. Although the configuration in whichthe leading end surface of the piezoelectric vibrator 20 is bonded tothe island-shaped part 35 while the piezoelectric vibrator 20 beingoff-center with respect to the effective displacement portion of thediaphragm portion 33 is exemplified in the first embodiment, theinvention is not limited thereto. The recording head 2 of the presentembodiment is characterized in that the island-shaped part 35 isdisposed being off-center with respect to the effective displacementportion of the diaphragm portion 33. More specifically, a center C3 ofthe island-shaped part 35 in the laminating direction is disposed beingoff-center, not toward one side (hereinafter referred to as a thirdside; corresponding to the first side in the first embodiment) buttowards the other side (hereinafter referred to as a fourth side;corresponding to the second side in the first embodiment) in thelaminating direction, that is, off-center toward the piezoelectricmaterial 41 s side (the ink supply port 27 side) with respect to thecenter C1 of the effective displacement portion in the laminatingdirection; note that the piezoelectric material 41 s is a layer at theside end, and is the inactive portion B of the piezoelectric vibrator20. The center C2 of the piezoelectric vibrator 20 in the laminatingdirection is disposed in a state in which the center C2 substantiallymatches the center C1 of the effective displacement portion.Accordingly, in a state in which the leading end surface of thepiezoelectric vibrator 20 is bonded to the island-shaped part 35, thelength of an extending portion of the island-shaped part 35 extended toboth sides in the laminating direction from the bonding portion of theisland-shaped part 35 and the piezoelectric vibrator 20 is longer at thefourth side than at the third side. That is, as for the length L3 of theextending portion on the third side and the length L4 of the extendingportion on the fourth side, a relation of L3<L4 holds. Further, also inthe present embodiment, the width W1 of the island-shaped part 25 on thefourth side (dimension in a direction orthogonal to the laminatingdirection) in the lengthwise direction of the island-shaped part 25(laminating direction of the piezoelectric vibrator 20) is wider thanthe width W2 on the third side in the same direction thereof.

As is described in the present embodiment, by making the island-shapedpart 35 be off-center toward the fourth side in the laminating directionwith respect to the effective displacement portion, an area of theisland-shaped part 35 disposed on the fourth side from the center C1 ofthe effective displacement portion in the laminating direction is widerthan an area of the island-shaped part 35 disposed on the third sidefrom the center C1 thereof. This makes it possible to make thedisplacement amounts of the regions on both sides from the center C1 ofthe effective displacement portion in the laminating direction beuniform when the piezoelectric vibrator 20 is driven. As a result, whilereducing the problems such as variation in the amount of ink ejectedthrough the nozzle 30, variation in the flying direction of the ink, andthe like caused by deflection in the displacement of the piezoelectricvibrator 20, it is possible to change the volume of the pressure chamber28 efficiently and stable through making use of an advantage of thepiezoelectric vibrator 20 that the displacement amount thereof can bemade larger. Since other configurations of the present embodiment arethe same as those of the first embodiment, detailed description thereofwill be omitted herein.

In the above embodiments, regarding the shape of the island-shaped part35, the configuration in which the island-shaped part 35 is shaped sothat the width W1 of the island-shaped part 35 on the fourth side in thelaminating direction is wider than the width W2 on the third side in thesame direction is exemplified. However, the shape is not limitedthereto, and the island-shaped part 35 whose widths on the third sideand the fourth side are constant can be employed. Also in this case, byemploying a configuration in which the piezoelectric vibrator 20 or theisland-shaped part 35 is disposed being off-center with respect to theeffective displacement portion, it is possible to make the displacementamounts of the regions on both sides from the center C1 of the effectivedisplacement portion in the laminating direction be uniform.

Regarding the configuration of the vibrator unit 16, the configurationin which the fixing plate 21 is bonded to the fourth side surface of thepiezoelectric vibrator 20 (in other words, the piezoelectric material 41s) at the base end portion 20 b side is exemplified; however, theconfiguration thereof is not limited thereto. For example, the presentinvention can be applied to a configuration in which the fixing plate 21is bonded to the base end surface of the piezoelectric vibrator 20(surface on the opposite side to the leading end surface to be bonded tothe island-shaped part 35) like the configuration of a vibrator unit 16′as a variation shown in FIG. 9. Further, the present invention can bealso applied to a configuration in which the fixing plate 21 is bondedto the surface of the third side of the piezoelectric vibrator 20(surface on the side where the external electrode is formed).

Thus far, the ink jet recording head 2, which is a type of a liquidejecting head, has been exemplified and explained. The present inventioncan be applied to other liquid ejecting heads configured to ejectliquids through nozzles by displacing island-shaped parts usingpiezoelectric vibrators to change a volume of the pressure chambers. Forexample, the present invention can be applied to coloring materialejecting heads mounted on display manufacturing apparatuses for themanufacture of color filters of liquid crystal displays or the like,electrode material ejecting heads mounted on electrode manufacturingapparatuses for the formation of electrodes of organic EL(electroluminescence) displays, surface emitting displays (FEDs) or thelike.

What is claimed is:
 1. A liquid ejecting head, comprising: a pressurechamber communicating with a nozzle, the pressure chamber extending in afirst direction; a vibration plate defining part of the pressurechamber, the vibrating plate having an effective displacement portionoverlapping with the pressure chamber in a plan view; and apiezoelectric vibrator being provided above the effective displacementportion so as to displace the effective displacement portion of thevibration plate, wherein the piezoelectric vibrator has a laminatestructure in which electrodes and piezoelectric material are alternatelylaminated in the first direction, a first outermost layer at one side ofthe laminate structure in the first direction is an electrode, a secondoutermost layer at the other side of the laminate structure in the firstdirection is a piezoelectric layer, a side of the laminate structure ofthe piezoelectric vibrator is located above the effective displacementportion of the vibration plate, and the side of the piezoelectricvibrator is laterally offset toward the other side in the firstdirection with respect to a center of the effective displacement portionin the first direction.
 2. The liquid ejecting head according to claim1, wherein the vibration plate includes an island-shaped part which isprovided in the effective displacement portion, the island-shaped partis on an opposite side of the effective displacement portion as thepressure chamber, and the island-shaped part is bonded to the side ofthe piezoelectric vibrator, the island-shaped part is located on thecenter of the effective displacement portion in the first direction, anda first length in the first direction between a first edge of theisland-shaped part and a surface of the first outermost layer is longerthan a second length in the first direction between a second edge of theisland-shaped part and a surface of the second outermost layer.
 3. Theliquid ejecting head according to claim 2, wherein a first width of thefirst edge in a second direction intersecting with the first directionis narrower than a second width of the second edge in the seconddirection.
 4. The liquid ejecting head according to claim 1, wherein aratio of a dimension of the island-shaped part to a dimension of theeffective displacement portion in the first direction is equal to ormore than 0.85.
 5. The liquid ejecting head according to claim 1,wherein a fixing plate is bonded to the piezoelectric vibrator at aposition opposite to a bonding interface where the island-shaped part isbonded with the piezoelectric vibrator.
 6. A liquid ejecting head,comprising: a pressure chamber communicating with a nozzle, the pressurechamber extending in a first direction; a vibration plate defining partof the pressure chamber, the vibrating plate having an effectivedisplacement portion overlapping with the pressure chamber in a planview; a piezoelectric vibrator being provided above the effectivedisplacement portion so as to displace the effective displacementportion of the vibration plate; an island-shaped part provided in theeffective displacement portion, the island-shaped part being on anopposite side of the effective displacement portion as the pressurechamber, wherein the piezoelectric vibrator has a laminate structure inwhich electrodes and piezoelectric material are alternately laminated inthe first direction, a first outermost layer at one side of the laminatestructure in the first direction is an electrode, a second outermostlayer at the other side of the laminate structure in the first directionis a piezoelectric layer, a side of the laminate structure of thepiezoelectric vibrator is located above the effective displacementportion of the vibration plate, the island-shaped part is bonded to theside of the piezoelectric vibrator, and the island-shaped part islaterally offset toward the other side in the first direction withrespect to a center of the effective displacement portion in the firstdirection.
 7. The liquid ejecting head according to claim 6, wherein thepiezoelectric vibrator is located on the center of the effectivedisplacement portion in the first direction, and a first length in thefirst direction between a first edge of the island-shaped part and asurface of the first outermost layer is shorter than a second length inthe first direction between a second edge of the island-shaped part anda surface of the second outermost layer.
 8. A liquid ejecting apparatuscomprising the liquid ejecting head according to claim
 1. 9. A liquidejecting apparatus comprising the liquid ejecting head according toclaim
 2. 10. A liquid ejecting apparatus comprising the liquid ejectinghead according to claim
 3. 11. A liquid ejecting apparatus comprisingthe liquid ejecting head according to claim
 4. 12. A liquid ejectingapparatus comprising the liquid ejecting head according to claim
 5. 13.A liquid ejecting apparatus comprising the liquid ejecting headaccording to claim
 6. 14. A liquid ejecting apparatus comprising theliquid ejecting head according to claim
 7. 15. A liquid ejecting head,comprising: a pressure chamber communicating with a nozzle, the pressurechamber extending in a first direction; a vibration plate defining awall of the pressure chamber, the vibrating plate having a movable partoverlapping with the pressure chamber in a plan view; and apiezoelectric vibrator being provided above the movable part so as tomove the movable part of the vibration plate, the piezoelectric vibratorbeing a laminate structure in which electrodes and piezoelectricmaterial are laminated, the piezoelectric vibrator having first andsecond outermost layers in the first direction, wherein the firstoutermost layer at one side of the laminate structure in the firstdirection is an electrode, and the second outermost layer at the otherside of the laminate structure in the first direction is a piezoelectriclayer, a side of the laminate structure of the piezoelectric vibrator islocated above the movable part of the vibration plate, and the side ofthe piezoelectric vibrator is laterally offset toward the other side inthe first direction with respect to a center of the movable part in thefirst direction.
 16. The liquid ejecting head according to claim 15,wherein the vibration plate includes an island-shaped member in themovable part, and the island-shaped member is bonded to the side of thepiezoelectric vibrator, a center of the island-shaped part in the firstdirection is located on the center of the movable part in the firstdirection, and the side of the piezoelectric vibrator is laterallyoffset relative to the center of the island-shaped member in the firstdirection.